Preliminary NMR relaxation studies have shown that, without assumption concerning a particular motional model, the B DNA helix is not rigid, but instead experiences large-amplitude fluctuations of nucleotide geometry which occur with a time constant near 1 nsec. The magnitude and timescale of those motions do not appear to change when DNA is wrapped to form the nucleosome core particle. Here we propose to study those DNA internal motions in some detail. We will study base plane motions by measuring 2H NMR relaxation times T1 and T2 of chicken erythrocyte core particles and monodisperse fragments of uncomplexed DNA which have been selectively 2H labeled at purine carbon C8. We will study deoxyribose sugar motions, as well as base plane motions, by measuring 13C NMR relaxation parameters (T1, T2, NOE) of monodisperse DNA fragments prepared from Chlorella Vulgaris which has been isotopically labeled with 13C. We will also reconstitute Chlorella DNA with unlabeled histones to form 13C labeled core particles, then use 13C NMR relaxation to study DNA internal motions in the nucleosome. In all of these solution-state experiments we will use phosphorescence anisotropy decay and transient electric dichroism to measure the overall motion of nucleosomes and DNA fragments. Once overall motions have been eliminated as unknown quantities, DNA internal motion can be calculated with greater accuracy. The fast nucleotide motions which have been measured in solution are in conflict with the rigid structure DNA inferred from x-ray diffraction studies. We propose to resolve that conflict, using solid-state NMR techniques to monitor DNA internal motions in the solid state. By measuring 13C and 13P relaxation parameters, we can determine if DNA internal motions have been "frozen out" in the solid or if they persist, but have not been overlooked due to the poor resolution of x-ray fiber diffraction studies.